1. Field of the Invention
The present invention relates to an apparatus for crack splitting a rod (shaft) and a big-end cap of a connecting rod, including a fixed expander mandrel half on a fixed part of the apparatus, a movable expander mandrel half on a part of the apparatus movable in the expanding direction and including supporting elements for rod and cap.
2. Description of the Related Art
Known from European patent document no. EO 0 396 797 is an apparatus for crack splitting rod and cap, including advanceable supporting elements on both the movable and fixed parts of the apparatus. In this known art, the advanceable supporting elements are formed by set screws (illustrated symbolically as grub screws). Turning the set screws permits advancing the supporting elements to clamp the connecting rod to be split relative to the fixed and movable expander mandrel halves in the apparatus. Experience has shown that clamping in place the connecting rod to be split, especially to prevent it from turning out of place, is necessary to achieve a defined crack with no negative bending effects.
With the advanceable supporting elements, it is also possible to set the apparatus for crack splitting rod and cap of connecting rods of various sizes. In addition, with the advanceable supporting elements, differences due to manufacturing tolerances can also be compensated for.
To achieve speedy adaptation, it is known to use powered advanceable supporting elements. In the case of both manual set screws and powered advanceable supporting elements, there is the problem that the advanceable supporting elements provided on the movable part of the apparatus are exposed to shock and vibration that is inherently involved in the crack splitting. Thus, in splitting, the two expander mandrel halves are usually urged apart with the aid of a cleaving wedge. This movement and splitting of the cap from the rod occurs abruptly. In addition, the movable part of the apparatus impacts a stop at which the movement of the movable part of the apparatus is halted. Powered advanceable supporting elements are especially heavily stressed by this action, resulting in problems with proper functioning and long useful life.
The present invention provides an apparatus for crack splitting the rod (shaft) and big-end cap of a connecting rod. The apparatus has a long useful life with no functioning problems. With the apparatus, the rod and the big-end cap of a connecting rod can be split with high precision. The advanceable supporting elements are arranged on a fixed part of the apparatus and the fixed supporting elements are arranged on the movable part of the apparatus.
In the present invention, the advanceable supporting elements, automatically exposed to more stress, are provided on the fixed part of the apparatus to thus significantly reduce the problems involved in reliable functioning and long useful life. This is particularly important where use is made of powered advanceable supporting elements, which are usually powered by pneumatic or hydraulic cylinders or by electric motor drives which are not only in themselves sensitive to shock and vibration but also incorporate flexible input and output tubing for supply and control. Flexible input and output tubing in pneumatic, hydraulic or electric motor drives are particularly sensitive to shock and vibration and cyclic stresses of reciprocating operation. Arranging these sensitive parts on the fixed part of the apparatus in accordance with the invention avoids the resulting loads and at least the influence of direct shock and vibration which is particularly damaging to flexible tubing and electric wiring.
Since the big-end caps of connecting rods always need to have outer contact surface areas for the bolts for connecting rod and cap, the cap can be supported particularly effectively at these contact surface areas. In one embodiment of the present invention, the fixed part of the apparatus is equipped to mount the cap and the movable part of the apparatus is equipped to mount the rod. In this arrangement, the rod is held particular simply and effectively in the apparatus when at least one fixed supporting element is formed by a locating peg for mounting the small-end bore of the rod.
As an alternative, the fixed supporting element may also be formed by a recess at least partially contacting suitable portions of the outer surface area of the rod end (small-end).
One particularly effective feature of the advanceable supporting elements is that they contact at least one shiftable wedge element substantially transversely to the advance movement. Such an arrangement enables a particular rigid arrangement to be achieved for loading. Advantageously in this arrangement, two supporting elements are provided and a wedge element is assigned to each supporting element. Thus, it is possible to benefit from the advantages of wedge actuation whilst simultaneously clamping the connecting rod reliably in place at two opposite locations.
By adapting the advance movement of each supporting element to uniformly clamp in place the connecting rod to be split, both wedge elements include wedge surface areas having an identical angle of attack. This thus achieves for both supporting elements an identical advance movement in such a configuration when both wedge elements are shifted by the same amount.
Production tolerance inaccuracies on the part of the connecting rod to be supported can be compensated for in that two advanceable supporting elements are provided, each of which can be advanced independently of the other. Due to the two supporting elements, each advanceable independently of the other, each connecting rod part to be fixedly secured can be individually set.
Auto-centering by actuating the wedge elements is simply achieved in that the wedge surface areas of the wedge elements are arranged opposite in angle of attack. Further, a hydraulic or pneumatic cylinder is provided whose face cooperates with the one wedge element and whose piston cooperates with the other wedge element. However, a particularly effective actuation of the advanceable supporting elements is also achievable by direct-acting hydraulic cylinders. This enables each supporting element in such a case to be connected to the piston rod of a supporting piston. This connection is configured to advantage such that each of the supporting elements may be arranged directly at the front end of the piston rod of the pistons.
For loading the connecting rods into the crack splitting apparatus, a loading device holds the crack splitting apparatus substantially stationary whilst the connecting rods are inserted therein. In such a configuration, the pneumatic or hydraulic cylinders or the electric motor drives including the feed and discharge lines for supply and control can be stationary whilst loading is achieved exclusively by moving the connecting rod.
There are basically two possibilities available for the loading arrangement. In the one possibility, a transport device may be arranged above the stationary apparatus for overhead insertion/removal of the connecting rod into/from the apparatus. In the other possibility, a clocked transport device is provided under the stationary apparatus from which the connecting rod is picked out for insertion into the apparatus, held in the apparatus during crack splitting, and then lowered back into the transport device.
To protect the sensitive drive system including the feed and discharge lines from indirect shock and vibration, the apparatus is mounted on a baseframe via shock absorbers.